)
@музыка:
@настроение:
Точно знаю, что надо сбросить пару кг
и пока не вернутся мои торчащие кости
я не успокоюсь
@настроение:
Печенье с шоколадом
печенье с желе
пуддинг с манго и пуддинг с личи
ванильный десерт 
и булочки с вишневым джемом
, но так как я не сдала зачёт, то мне можно и нажраться сладкого
В общем вот какие у нас оппы и сэмпаи
Electromagnetism is the force that causes the interaction between electrically charged particles; the areas in which this happens are called electromagnetic fields. It is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation.
Electromagnetism is the interaction responsible for practically all
the phenomena encountered in daily life, with the exception of gravity.
Ordinary matter takes its form as a result of intermolecular forces between individual molecules in matter. Electrons are bound by electromagnetic wave mechanics into orbitals around atomic nuclei to form atoms, which are the building blocks of molecules. This governs the processes involved in chemistry, which arise from interactions between the electrons
of neighboring atoms, which are in turn determined by the interaction
between electromagnetic force and the momentum of the electrons.
Electromagnetism manifests as both electric fields and magnetic fields.
Both fields are simply different aspects of electromagnetism, and hence
are intrinsically related. Thus, a changing electric field generates a
magnetic field; conversely a changing magnetic field generates an
electric field. This effect is called electromagnetic induction, and is the basis of operation for electrical generators, induction motors, and transformers. Mathematically speaking, magnetic fields and electric fields are convertible with relative motion as a 2nd-order tensor or bivector.
Electric fields are the cause of several common phenomena, such as electric potential (such as the voltage of a battery) and electric current (such as the flow of electricity through a flashlight). Magnetic fields are the cause of the force associated with magnets.
In quantum electrodynamics, electromagnetic interactions between charged particles can be calculated using the method of Feynman diagrams, in which we picture messenger particles called virtual photons being exchanged between charged particles. This method can be derived from the field picture through perturbation theory.
The theoretical implications of electromagnetism led to the development of special relativity by Albert Einstein in 1905.
Originally electricity and magnetism were thought of as two separate
forces. This view changed, however, with the publication of James Clerk Maxwell's 1873 Treatise on Electricity and Magnetism
in which the interactions of positive and negative charges were shown
to be regulated by one force. There are four main effects resulting from
these interactions, all of which have been clearly demonstrated by
experiments:
While preparing for an evening lecture on 21 April 1820, Hans Christian Ørsted made a surprising observation. As he was setting up his materials, he noticed a compass needle deflected from magnetic north
when the electric current from the battery he was using was switched on
and off. This deflection convinced him that magnetic fields radiate
from all sides of a wire carrying an electric current, just as light and
heat do, and that it confirmed a direct relationship between
electricity and magnetism.
At the time of discovery, Ørsted did not suggest any satisfactory
explanation of the phenomenon, nor did he try to represent the
phenomenon in a mathematical framework. However, three months later he
began more intensive investigations. Soon thereafter he published his
findings, proving that an electric current produces a magnetic field as
it flows through a wire. The CGS unit of magnetic induction (oersted) is named in honor of his contributions to the field of electromagnetism.
His findings resulted in intensive research throughout the scientific community in electrodynamics. They influenced French physicist André-Marie Ampère's
developments of a single mathematical form to represent the magnetic
forces between current-carrying conductors. Ørsted's discovery also
represented a major step toward a unified concept of energy.
This unification, which was observed by Michael Faraday, extended by James Clerk Maxwell, and partially reformulated by Oliver Heaviside and Heinrich Hertz, is one of the key accomplishments of 19th century mathematical physics. It had far-reaching consequences, one of which was the understanding of the nature of light. Light and other electromagnetic waves take the form of quantized, self-propagating oscillatory electromagnetic field disturbances called photons. Different frequencies of oscillation give rise to the different forms of electromagnetic radiation, from radio waves at the lowest frequencies, to visible light at intermediate frequencies, to gamma rays at the highest frequencies.
Ørsted was not the only person to examine the relation between electricity and magnetism. In 1802 Gian Domenico Romagnosi, an Italian legal scholar, deflected a magnetic needle by electrostatic charges. Actually, no galvanic
current existed in the setup and hence no electromagnetism was present.
An account of the discovery was published in 1802 in an Italian
newspaper, but it was largely overlooked by the contemporary scientific
community.[1]
The electromagnetic force is one of the four known fundamental forces. The other fundamental forces are: the strong nuclear force, which binds quarks to form nucleons, and binds nucleons to form nuclei, the weak nuclear force, which causes certain forms of radioactive decay, and the gravitational force. All other forces (e.g. friction) are ultimately derived from these fundamental forces and momentum carried by the movement of particles.
The electromagnetic force is the one responsible for practically all
the phenomena one encounters in daily life above the nuclear scale, with
the exception of gravity. Roughly speaking, all the forces involved in
interactions between atoms can be explained by the electromagnetic force acting on the electrically charged atomic nuclei and electrons
inside and around the atoms, together with how these particles carry
momentum by their movement. This includes the forces we experience in
"pushing" or "pulling" ordinary material objects, which come from the intermolecular forces between the individual molecules in our bodies and those in the objects. It also includes all forms of chemical phenomena.
A necessary part of understanding the intra-atomic to intermolecular
forces is the effective force generated by the momentum of the
electrons' movement, and that electrons move between interacting atoms,
carrying momentum with them. As a collection of electrons becomes more
confined, their minimum momentum necessarily increases due to the Pauli exclusion principle.
The behaviour of matter at the molecular scale including its density is
determined by the balance between the electromagnetic force and the
force generated by the exchange of momentum carried by the electrons
themselves.
The scientist William Gilbert proposed, in his De Magnete
(1600), that electricity and magnetism, while both capable of causing
attraction and repulsion of objects, were distinct effects. Mariners had
noticed that lightning strikes had the ability to disturb a compass
needle, but the link between lightning and electricity was not confirmed
until Benjamin Franklin's
proposed experiments in 1752. One of the first to discover and publish a
link between man-made electric current and magnetism was Romagnosi, who in 1802 noticed that connecting a wire across a voltaic pile deflected a nearby compass needle. However, the effect did not become widely known until 1820, when Ørsted performed a similar experiment.[2] Ørsted's work influenced Ampère to produce a theory of electromagnetism that set the subject on a mathematical foundation.
A theory of electromagnetism, known as classical electromagnetism, was developed by various physicists over the course of the 19th century, culminating in the work of James Clerk Maxwell,
who unified the preceding developments into a single theory and
discovered the electromagnetic nature of light. In classical
electromagnetism, the electromagnetic field obeys a set of equations
known as Maxwell's equations, and the electromagnetic force is given by the Lorentz force law.
One of the peculiarities of classical electromagnetism is that it is difficult to reconcile with classical mechanics, but it is compatible with special relativity. According to Maxwell's equations, the speed of light in a vacuum is a universal constant, dependent only on the electrical permittivity and magnetic permeability of free space. This violates Galilean invariance, a long-standing cornerstone of classical mechanics. One way to reconcile the two theories is to assume the existence of a luminiferous aether
through which the light propagates. However, subsequent experimental
efforts failed to detect the presence of the aether. After important
contributions of Hendrik Lorentz and Henri Poincaré,
in 1905, Albert Einstein solved the problem with the introduction of
special relativity, which replaces classical kinematics with a new
theory of kinematics that is compatible with classical electromagnetism.
(For more information, see History of special relativity.)
In addition, relativity theory shows that in moving frames of
reference a magnetic field transforms to a field with a nonzero electric
component and vice versa; thus firmly showing that they are two sides
of the same coin, and thus the term "electromagnetism". (For more
information, see Classical electromagnetism and special relativity.)
In another paper published in that same year, Albert Einstein
undermined the very foundations of classical electromagnetism. His
theory of the photoelectric effect
(for which he won the Nobel prize for physics) posited that light could
exist in discrete particle-like quantities, which later came to be
known as photons. Einstein's theory of the photoelectric effect extended the insights that appeared in the solution of the ultraviolet catastrophe presented by Max Planck
in 1900. In his work, Planck showed that hot objects emit
electromagnetic radiation in discrete packets, which leads to a finite
total energy emitted as black body radiation.
Both of these results were in direct contradiction with the classical
view of light as a continuous wave. Planck's and Einstein's theories
were progenitors of quantum mechanics,
which, when formulated in 1925, necessitated the invention of a quantum
theory of electromagnetism. This theory, completed in the 1940s, is
known as quantum electrodynamics (or "QED"
, and, in situations where perturbation theory is applicable, is one of the most accurate theories known to physics.
